Avaliação dos distúrbios da hemostasia secundária causados pela presença da peçonha bruta ou de proteínas isoladas da peçonha da serpente Crotalus durissus terrificus

Abstract

Among the activities triggered by Crotalus durissus terrificus snake venom, coagulation is both intriguing and contradictory since the venom contains in its composition both coagulant and anticoagulant precursor proteins. This work describes the in vitro effects of crude venom and purified proteins from Crotalus durissus terrificus snake venom as they affect coagulation factors of the extrinsic, intrinsic, and common clotting pathways in citrated human plasma. Coagulant activity and/or anticoagulant crude venom, and purified proteins were all analyzed directly in citrated human plasma, and Prothrombin Time (PT), Activated Partial Thromboplastin Time (APTT) and coagulation factors were analyzed using commercial kits. Clots formed by the presence of crude venom and Gyroxin presented as flexible hyaline masses in punctiform distribution. The evaluation of clot formation time in the presence of the isolated proteins (Crotoxin complex, Crotoxin A, Crotoxin B and Crotamine) with commercial assays (PT and APTT) made it possible to infer that these proteins interfere in all pathways of the coagulation cascade. Crotoxin B can inhibit prothrombinase complex formation by direct interaction with factor Xa. However, regarding ophidism (snake venom poisoning) by C. d. terrificus, Gyroxin acts directly, breaking down fibrinogen to fibrin and increasing the amount plasminogen activator (an inhibitor), which results in the formation of thrombi. The Crotoxin complex, Crotoxin A, Crotoxin B and proteins can act in prothrombinase complex formation, and Crotamine interacts with negatively charged regions of differing coagulation factors in all coagulation pathways, and possesses a whole set of activities causing dysfunction, activation and/or inhibition of natural anticoagulants and disturbing hemostasis.